Make `defmacrocallback` to be shown via IEx `b` helper
Make `defmacrocallback` to be shown via IEx `b` helper

antipax/elixir,ggcampinho/elixir,elixir-lang/elixir,kelvinst/elixir,lexmag/elixir,kelvinst/elixir,kimshrier/elixir,kimshrier/elixir,antipax/elixir,beedub/elixir,joshprice/elixir,pedrosnk/elixir,pedrosnk/elixir,michalmuskala/elixir,gfvcastro/elixir,gfvcastro/elixir,beedub/elixir,ggcampinho/elixir,lexmag/elixir